EventFilter - MoveMouse event changes position every pixel

[Grzyboo]

I'm making some draggable widgets. Labels work fine any way I do it, but there is obviously a problem with PlainTextEdits. I've installed an EventFilter on PlainTextEdit's viewport and want to drag the whole widget with mouse movement.

bool FilerPlainText2Click::eventFilter(QObject* object, QEvent* event)
{
    if(event->type() == QEvent::MouseButtonDblClick)
        //some code here (set pSelectedWidget)
    else if(event->type() == QEvent::MouseButtonPress && ((QMouseEvent*)event)->button() == Qt::LeftButton)
        //some code here (set bDragging true)
    else if(event->type() == QEvent::MouseMove)
    {
        QWidget* pSelected = ((QWidget*)object)->parentWidget(); // pointer to the whole widget
        MainWindow* pWin = (MainWindow*)pSelected->window(); // pointer to the main window, which this widget is placed in
 
        if(pWin->bDragging)
        {
            QMouseEvent* mEvent = (QMouseEvent*)event;
            int x = mEvent->x() - pWin->iDraggingDistX;
            int y = mEvent->y() - pWin->iDraggingDistY;
            QRect rect(x, y, pWin->pSelectedWidget->width(), pWin->pSelectedWidget->height());
            pWin->pSelectedWidget->setGeometry(rect);
 
            qDebug() << "mEvent pos: " << mEvent->x() << " | " << mEvent->y();
        }
        return true;
    }
    else
       return QObject::eventFilter(object,event);
}

bool FilerPlainText2Click::eventFilter(QObject* object, QEvent* event)
{
    if(event->type() == QEvent::MouseButtonDblClick)
        //some code here (set pSelectedWidget)
    else if(event->type() == QEvent::MouseButtonPress && ((QMouseEvent*)event)->button() == Qt::LeftButton)
        //some code here (set bDragging true)
    else if(event->type() == QEvent::MouseMove)
    {
        QWidget* pSelected = ((QWidget*)object)->parentWidget(); // pointer to the whole widget
        MainWindow* pWin = (MainWindow*)pSelected->window(); // pointer to the main window, which this widget is placed in

        if(pWin->bDragging)
        {
            QMouseEvent* mEvent = (QMouseEvent*)event;
            int x = mEvent->x() - pWin->iDraggingDistX;
            int y = mEvent->y() - pWin->iDraggingDistY;
            QRect rect(x, y, pWin->pSelectedWidget->width(), pWin->pSelectedWidget->height());
            pWin->pSelectedWidget->setGeometry(rect);

            qDebug() << "mEvent pos: " << mEvent->x() << " | " << mEvent->y();
        }
        return true;
    }
    else
       return QObject::eventFilter(object,event);
}

To copy to clipboard, switch view to plain text mode 

Explanation:

iDraggingDistX / iDraggingDistY - distance between grabbed point and left top corner of the widget
pSelectedWidget - the widget we're dragging

iDraggingDistX / iDraggingDistY - distance between grabbed point and left top corner of the widget
pSelectedWidget - the widget we're dragging

To copy to clipboard, switch view to plain text mode 

qDebug's effect:

mEvent pos:  217  |  462
mEvent pos:  127  |  62
mEvent pos:  216  |  462
mEvent pos:  126  |  62
mEvent pos:  216  |  463
mEvent pos:  125  |  62
mEvent pos:  215  |  463
mEvent pos:  124  |  62
mEvent pos:  215  |  464
mEvent pos:  123  |  62

mEvent pos:  217  |  462
mEvent pos:  127  |  62
mEvent pos:  216  |  462
mEvent pos:  126  |  62
mEvent pos:  216  |  463
mEvent pos:  125  |  62
mEvent pos:  215  |  463
mEvent pos:  124  |  62
mEvent pos:  215  |  464
mEvent pos:  123  |  62

To copy to clipboard, switch view to plain text mode 

For some reason every time i move my widget by 1 pixel, mEvent's coordinates change (they seem to be realtive to widget once and relative to main window second time). My widget is obviously blinking in both positions. Why is this?
I realise it may sound very confusing and i might not be clear enough. Adding a video for clarity.

[anda_skoa]

You could try to map the coordinates to global coordinates and do the distance calculation in that domain.

Cheers,
_

[Grzyboo]

Thanks a lot! It helped.